Hispanic women have the highest lifetime risk for type 2 diabetes (T2DM). A window of opportunity for preventing T2DM exists for women with pregnancies complicated by gestational diabetes mellitus (GDM). Women with prior GDM face increased risk of T2DM. Hispanic women are at increased risk of GDM, and those with GDM have higher relative risks for developing T2DM than non-Hispanic white women with GDM. The NIH-funded Diabetes Prevention Program (DPP) documented the effectiveness of lifestyle modification to prevent T2DM. Translating DPP research into community-based settings has been challenging. Recent development of mobile technologies offers promising solutions to taking knowledge obtained from experimental settings into community-based care. The proposed SBIR, building on the team's CDC-funded internet-based, GDM-modified DPP, would be the first to develop and test an interactive, culturally and individually-tailored, plain languae Spanish/English mobile health intervention (m-intervention) to reduce risk of T2DM for Hispanic women with recent GDM. The m-intervention leverages the widespread adoption of mobile phones in Hispanic women of reproductive age, and affords the opportunity to overcome physical barriers (accessible 24/7), knowledge barriers (education/skills development in plain Spanish/English), infrastructure barriers (not present using mobile phones), economic barriers (affordable), and cultural barriers (culturally acceptable). Using mobile phones to prevent T2DM in Hispanic women with prior GDM addresses the RFA's goal for...existing technologies that have been redesigned based on the needs of a specific health disparity population. The proposed system is technologically innovative using participant-generated text messages for themselves as well as others. The Spanish/English mobile app features: culturally/individually tailored educational/motivational texts for behavioral change; algorithm-derived, individually tailored texts that are a) participant generated; b) automated, based on prior participant-defined schedule, and c) just in-time, based on real time participant input about current activities; and weight tracking. Our long-term goal is the prevention of T2DM in this at-risk population. Formative evaluations test the cultural acceptability of the texts and the usability of the app. A pilot randomized trial explores effectiveness of the app in changes in self-efficacy for healthy eating (primary outcome), weight loss (secondary outcome), and HBA1C, perceived risk for T2DM, and modified perceived risk (exploratory). Phase I results will provide data to determine sample size for the development/submission of a Phase II RCT of the m-intervention to promote healthy lifestyle to achieve weight loss among Hispanic women with recent GDM. The m-intervention offers potential of a scalable and cost-effective approach to decreasing health disparities and to improving health outcomes in Hispanic women with recent GDM, a high-risk, yet underserved group. The proposed application has broad commercialization potential given changes in health care delivery.